Tue·Mar 3, 2020Tuesday·March 3, 2020

1. 01*

   Comment on "Testing claims of the GW170817 binary neutron star inspiral affecting $\beta$-decay rates''

   E. Fischbach🇺🇸 · D. E. Krause🇺🇸 · M. Pattermann🇺🇸

   We show that recently reported radioactive decay data support an earlier observation of an unexpected signal associated with the GW170817 binary neutron star inspiral.

   nucl-ex3 citations
2. 02*

   Polarization transfer to bound protons measured by quasi-elastic electron scattering on ${}^{12}$C

   Tilen Brecelj · Sebouh J. Paul · Tim Kolar · Patrick Achenbach · Adi Ashkenazi · Ralph Böhm · Erez O. Cohen · Michael O. Distler · Anselm Esser · Ronald Gilman · Carlotta Giusti · David Izraeli and 20 other authors

   We report the measurements of the transverse ($P^{\prime }x$) and longitudinal ($P^{\prime }z$) components of the polarization transfer to a bound proton in carbon via the quasi-free ${}^{12}\mathrm{C}(\vec{e},e^{\prime }\vec{p})$ reaction, over a wide range of missing momenta. We determine these polarization-transfers separately for protons knocked out from the $s$- and $p$-shells. The electron-beam polarization was measured to determine the individual components with systematic uncertainties which allow a detailed comparison with theoretical calculations.

   nucl-exPRC(2020)·9 citations
3. 03*

   The possibility to study in-medium modification of $J/\psi$ mesons from their photoproduction on nuclei near threshold in the case of presence of the LHCb pentaquark states $P_c^{+}$ in this photoproduction

   E. Ya. Paryev🇷🇺

   We study the $J/\psi$ photoproduction from nuclei in the near-threshold beam energy region of $E_{\gamma }$=5--11 GeV within the nuclear spectral function approach by considering incoherent direct ($\gamma N\to J/\psi N$) and two-step ($\gamma p\to P_c^{+}(4312)$, $P_c^{+}(4312)\to J/\psi p$; $\gamma p\to P_c^{+}(4440)$, $P_c^{+}(4440)\to J/\psi p$; $\gamma p\to P_c^{+}(4457)$, $P_c^{+}(4457)\to J/\psi p$) $J/\psi$ production processes. We calculate the absolute excitation functions for the non-resonant and resonant production of $J/\psi$ mesons off ${}^{12}$C and ${}^{208}$Pb target nuclei within the different scenarios for in-medium modification of the directly photoproduced $J/\psi$ mesons and for branching ratios of the decays $P_c^{+}(4312)\to J/\psi p$, $P_c^{+}(4440)\to J/\psi p$ and $P_c^{+}(4457)\to J/\psi p$. We show that the non-resonant subthreshold $J/\psi$ production in $\gamma A$ reactions reveals some sensitivity to employed in-medium modification scenarios for $J/\psi$ mesons, which is not masked by the resonantly produced $J/\psi$ mesons, only if above branching ratios are less than 5\%. We also demonstrate that if these branching ratios more than 5\% then the presence of the $P_c^{+}(4312)$, $P_c^{+}(4440)$ and $P_c^{+}(4457)$ resonances in $J/\psi$ photoproduction on nuclei produces above threshold additional enhancements in the behavior of the total $J/\psi$ creation cross section on nuclei, which could be also studied in the future JLab experiments at the CEBAF facility to provide both further evidence for their existence and valuable information on their nature.

   ↳ nucl-thnucl-exNPA(2020)·9 citations
4. 04*

   The single-particle unit for alpha decay

   Chong Qi🇸🇪 · Roberto Liotta🇸🇪 · Ramon Wyss🇸🇪

   A salient feature of quantum mechanics is the inherent property of collective quantum motion, when apparent independent quasiparticles move in highly correlated trajectories, resulting in strongly enhanced transition probabilities. To assess the extend of a collective quantity requires an appropriate definition of the uncorrelated average motion, often expressed by single particle units. A well known example in nuclear physics is the Weisskopf unit for electromagnetic transitions which reveals different aspects of collective motion. In this paper we define the corresponding single particle unit for alpha decay following Weisskopf's derivations. We evaluate the alpha decay amplitude as induced by four uncorrelated/non-interacting protons and neutrons and compare it with the one extracted from observed decay rates. Our definition elucidates the collectivity in alpha decay and facilitates an unified description of all alpha decay processes along the nuclear chart. Our formalism is also applicable to other particle decay processes.

   ↳ nucl-thnucl-exPLB(2021)·7 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.